/*******************************************************************************
 * Copyright (c) 2011 MadRobot.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Lesser Public License v2.1
 * which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * 
 * Contributors:
 *  Elton Kent - initial API and implementation
 ******************************************************************************/
package com.madrobot.beans;

import java.beans.PropertyChangeListener;

/* A PropertyEditor class provides support for GUIs that want to
 * allow users to edit a property value of a given type.
 * <p>
 * PropertyEditor supports a variety of different kinds of ways of
 * displaying and updating property values. Most PropertyEditors will
 * only need to support a subset of the different options available in
 * this API.
 * <P>
 * Simple PropertyEditors may only support the getAsText and setAsText
 * methods and need not support (say) paintValue or getCustomEditor. More
 * complex types may be unable to support getAsText and setAsText but will
 * instead support paintValue and getCustomEditor.
 * <p>
 * Every propertyEditor must support one or more of the three simple
 * display styles. Thus it can either (1) support isPaintable or (2)
 * both return a non-null String[] from getTags() and return a non-null
 * value from getAsText or (3) simply return a non-null String from
 * getAsText().
 * <p>
 * Every property editor must support a call on setValue when the argument
 * object is of the type for which this is the corresponding propertyEditor.
 * In addition, each property editor must either support a custom editor,
 * or support setAsText.
 * <p>
 * Each PropertyEditor should have a null constructor.
 */

public interface PropertyEditor {

	/**
	 * Set (or change) the object that is to be edited. Primitive types such
	 * as "int" must be wrapped as the corresponding object type such as
	 * "java.lang.Integer".
	 * 
	 * @param value
	 *            The new target object to be edited. Note that this
	 *            object should not be modified by the PropertyEditor, rather
	 *            the PropertyEditor should create a new object to hold any
	 *            modified value.
	 */
	void setValue(Object value);

	/**
	 * Gets the property value.
	 * 
	 * @return The value of the property. Primitive types such as "int" will
	 *         be wrapped as the corresponding object type such as
	 *         "java.lang.Integer".
	 */

	Object getValue();

	// ----------------------------------------------------------------------

	/**
	 * Determines whether this property editor is paintable.
	 * 
	 * @return True if the class will honor the paintValue method.
	 */

	boolean isPaintable();

	/**
	 * Paint a representation of the value into a given area of screen
	 * real estate. Note that the propertyEditor is responsible for doing
	 * its own clipping so that it fits into the given rectangle.
	 * <p>
	 * If the PropertyEditor doesn't honor paint requests (see isPaintable) this
	 * method should be a silent noop.
	 * <p>
	 * The given Graphics object will have the default font, color, etc of the
	 * parent container. The PropertyEditor may change graphics attributes such
	 * as font and color and doesn't need to restore the old values.
	 * 
	 * @param gfx
	 *            Graphics object to paint into.
	 * @param box
	 *            Rectangle within graphics object into which we should paint.
	 */
	// void paintValue(java.awt.Graphics gfx, java.awt.Rectangle box);

	// ----------------------------------------------------------------------

	/**
	 * Returns a fragment of Java code that can be used to set a property
	 * to match the editors current state. This method is intended
	 * for use when generating Java code to reflect changes made through the
	 * property editor.
	 * <p>
	 * The code fragment should be context free and must be a legal Java
	 * expression as specified by the JLS.
	 * <p>
	 * Specifically, if the expression represents a computation then all classes
	 * and static members should be fully qualified. This rule applies to
	 * constructors, static methods and non primitive arguments.
	 * <p>
	 * Caution should be used when evaluating the expression as it may throw
	 * exceptions. In particular, code generators must ensure that generated
	 * code will compile in the presence of an expression that can throw checked
	 * exceptions.
	 * <p>
	 * Example results are:
	 * <ul>
	 * <li>Primitive expresssion: <code>2</code>
	 * <li>Class constructor: <code>new java.awt.Color(127,127,34)</code>
	 * <li>Static field: <code>java.awt.Color.orange</code>
	 * <li>Static method: <code>javax.swing.Box.createRigidArea(new
	 * java.awt.Dimension(0, 5))</code>
	 * </ul>
	 * 
	 * @return a fragment of Java code representing an initializer for the
	 *         current value. It should not contain a semi-colon
	 *         ('<code>;</code>') to end the expression.
	 */
	String getJavaInitializationString();

	// ----------------------------------------------------------------------

	/**
	 * Gets the property value as text.
	 * 
	 * @return The property value as a human editable string.
	 *         <p>
	 *         Returns null if the value can't be expressed as an editable
	 *         string.
	 *         <p>
	 *         If a non-null value is returned, then the PropertyEditor should
	 *         be prepared to parse that string back in setAsText().
	 */
	String getAsText();

	/**
	 * Set the property value by parsing a given String. May raise
	 * java.lang.IllegalArgumentException if either the String is
	 * badly formatted or if this kind of property can't be expressed
	 * as text.
	 * 
	 * @param text
	 *            The string to be parsed.
	 */
	void setAsText(String text) throws java.lang.IllegalArgumentException;

	// ----------------------------------------------------------------------

	/**
	 * If the property value must be one of a set of known tagged values,
	 * then this method should return an array of the tags. This can
	 * be used to represent (for example) enum values. If a PropertyEditor
	 * supports tags, then it should support the use of setAsText with
	 * a tag value as a way of setting the value and the use of getAsText
	 * to identify the current value.
	 * 
	 * @return The tag values for this property. May be null if this
	 *         property cannot be represented as a tagged value.
	 * 
	 */
	String[] getTags();

	// ----------------------------------------------------------------------

	/**
	 * A PropertyEditor may choose to make available a full custom Component
	 * that edits its property value. It is the responsibility of the
	 * PropertyEditor to hook itself up to its editor Component itself and
	 * to report property value changes by firing a PropertyChange event.
	 * <P>
	 * The higher-level code that calls getCustomEditor may either embed the
	 * Component in some larger property sheet, or it may put it in its own
	 * individual dialog, or ...
	 * 
	 * @return A java.awt.Component that will allow a human to directly
	 *         edit the current property value. May be null if this is
	 *         not supported.
	 */

	// java.awt.Component getCustomEditor();

	/**
	 * Determines whether this property editor supports a custom editor.
	 * 
	 * @return True if the propertyEditor can provide a custom editor.
	 */
	boolean supportsCustomEditor();

	// ----------------------------------------------------------------------

	/**
	 * Register a listener for the PropertyChange event. When a
	 * PropertyEditor changes its value it should fire a PropertyChange
	 * event on all registered PropertyChangeListeners, specifying the
	 * null value for the property name and itself as the source.
	 * 
	 * @param listener
	 *            An object to be invoked when a PropertyChange
	 *            event is fired.
	 */
	void addPropertyChangeListener(PropertyChangeListener listener);

	/**
	 * Remove a listener for the PropertyChange event.
	 * 
	 * @param listener
	 *            The PropertyChange listener to be removed.
	 */
	void removePropertyChangeListener(PropertyChangeListener listener);

}
